How sweet it is

Spring is here and with it comes the growth of new sap-rich leaves, particularly on eucalypt trees. This means that it is time for the sap-sucking insects to put in an appearance. Insects of the order Hemiptera make up a diverse range of creatures all distinguished by having sucking mouth-parts. The adult and young insects feed by either sucking the sap from the leaves and stems of plants or sucking the juices out of other insects.

Sap-sucking insects such as psyllids extrude a sugary substance called honeydew which they fashion into ‘houses’ under which they live. These houses are called lerps. Lerps are in turn the primary food source for birds such as pardalotes and bell miners.

Another sap-sucking insect around at the moment is the Gumtree Hopper (pictured above). Gumtree Hoppers also extrude honeydew which ants have found to be an energy-rich food source. If you look at the new growth on gum trees at the moment and you find it covered with ants, chances are the ants are ‘harvesting’ honeydew from the rear end of Gumtree Hoppers. The picture above shows an ant doing exactly that. The ant takes the honeydew back to the colony and stores it for later consumption. In return for this food the ants provide the hoppers with protection from predators and parasites.

If the ant is not there to collect the liquid it simply drops on the vegetation below (see picture above) to be collected by the ants at a later time. A tree supporting a large number of Gumtree Hoppers and their nymphs can become soaked in honeydew and have the sugary liquid literally dripping from the stems (pictured left). This in turn attracts bees which find the honeydew an attractive alternative to pollen.

How sweet it is.